Process for producing antistatic characteristic in nylon fibers



3,296,020 PROCESS FOR PRODUCING ANTISTATIC CHAR- ACTERISTIC IN NYLONFIBERS Robert E. Sheehan, Bibb Mfg. Co., Macon, Ga. 31202 No Drawing.Filed Aug. 27, 1964, Ser. No. 393,011 12 Claims. (Cl. 11'7138.8)

This application is a continuation-in-part of Serial No. 847,683, filedOctober 21, 1959.

This invention relates to the treatment of nylon fibers, yarns and tothe treatment of finished products incorporating such fibers. Moreparticularly, it relates to the treatment of such fibers and finished orsemi-finished products containing such fibers so as to improve theproducts obtained after such physical processing operations as carding,tufting and the like, or such chemical processing as dyeing and thelike, or other physical and chemical opera tions performed on suchfibers, for example, in the manufacture of fioor coverings.

For purposes of illustration, the invention will be described as itapplies to the manufacture of a floor covering material, but is it to beunderstood that the treatment disclosed is of general applicability andthat the description is therefore to be taken as illustrative ratherthan as limitative.

Several years ago nylon staple was introduced to the industry for floorcoverings of two types of cut pile rugs: the velvet type produced from acrimped heat-set staple which cannot be heat-set further, and a friezetype made from mechanically-crimped staple which can be further heat-setafter being made into yarn.

When introduced into the manufacture of cut pile rugs, yarns formed fromsuch staples were found to be extremely diflicult to dye or to finishinto rugs with a uniform non-Streaky appearance. The streakiness wasobserved at various stages during the processing of the nylon fibers, asindicated below.

The first production of nylon staple run through a carding apparatusinvariably had a dingy, soiled appearance which would change to auniform White after staple had been run through the machine for sometime. Later, in processing yarns from either beam or creel machines,e.g., in tufting the yarn, breaks, lap-ups and tangled ends were asource of difficulty. Finally, in dyeing the yarn, it was found thatstreaks present in the tufted nylon carpeting before dyeing invariablyappeared in the dyed product.

Briefly, in accordance with the present invention, these and otherdifficulties experienced in the physical and chemical processing ofnylon fibers have been considerably diminished and in many instanceshave been entirely eliminated, and uniformly dyed products free fromstreaky or non-uniform appearances have been obtained by treating thenylon at one or more stages of the manufacturing process withcomposition consisting principally of a product formed by theesterification of mixed fatty acids with alkyl glycols or glycerols, andpreferably containing, in addition, both a hygroscopic agent and a rustinhibitor.

While I do not wish to be bound by any specific explanation of themanner in which the invention operates, it is believed that many of thedifficulties heretofore experienced in both the chemical and physicalprocessing of nylon staple were the result of a pronounced tendency toaccumulate static electrical charges as a result of friction, rubbing orother physical or chemical causes, incident to processing of the nylon.

States Patent "ice . In accordance with the present invention, the firststep 111 eliminating the above-noted difficulties comprises removal ofany cationic agents or other agents previously applied, by the nylonproducer or other processors. Thereafter the nylon, now freed of anysurface conditioning agents, is sprayed with -or immersed in thecomposition of the present invention. The method of application is notcritical and may be either a batch procedure or a continuous process, asfacilities permit.

After treatment with the composition, it has been found that theafiinity of the nylon for dirt is greatly reduced and this isparticularly noticeable in carding, tufting and other processing whichis primarily physical. Further, it was observed that the treatmentresulted in products which would dye uniformly. The effect of thetreatment persists only as long as the treating agent remains present onthe nylon, and hence the treatment must be renewed after laundering ordyeing or other treatments involving the use of liquids, if thedestaticized effect is to persist in the resulting article.

Essentially the compositions of the present invention may comprise thefollowing:

(1) A fatty ester, such as the naturally occurring animal and vegetablefatty esters, and preferably comprising the product formed by theesterification of fatty acids and alkyl glycols or glycerols.

(2) A substance compatible with the fatty ester which tends to make asolution or dispersion of the fatty ester more hygroscopic, and

(3) A rust inhibitor compatible with the fatty ester.

The ester employed may be any of a number of preparations presentlyavailable commercially. Preferably the fatty acids to be esterfiedshould be those which are readily completely or almost completelyesterified by the glycol or glycerol. With esters formed by such fattyacids, little oxidation is experienced with the passage of time, and asa result, nylon fibers treated with the esters are not found to becomediscolored or yellowed on storage or on exposure to heat at 300 F. Theesterification is accomplished by known techniques and forms no part ofthe. present invention. Preferred fatty acids are stearic, oleic andpalmitic. In general, monocarboxylic aliphatic acids with at least 6carbon atoms in the alkyl chain are preferred. Whatever the acid, ormixture of acids used, the resulting fatty ester product intended foruse in the treatment of the fibers must be anionic or non-ionic. Itcannot be cationic if the desired results are to be obtained.Accordingly, the esters should preferably be free from such substituentsas amine groups as may be present in Sapamines, Avitex R, and otherknown textile fiber treating compositions.

The glycols and glycerols with which the fatty acids are esterified arepreferably short chain polyols, such as ethylene glycol, diethyleneglycol, hexalene glycol, or glycerols such as penta glycerol, therelative proportions of fatty acids to glycols being roughly thoserequired to produce a saturated, completely esterified product. Mixedesters and mixtures of esters may be used as well as the pure compounds.

Since the treatment of the invention is being applied to hydrophobicsubstances, it has been found advantageous to add a hygroscopic agent tothe ester to make the preparation more hydrophilic. The hygroscopicadditive should constitute between about 5 to 30% of the totalpreparation, with 15 to 25% being preferred, al-

though the relative proportions do not appear to be critical.

Any hygroscopic agent compatible with the fatty acid ester may be used.Typical useful hygroscopic agents are: diethylene glycol,diethanolamine, triethylene glycol, glycerine, triethan-olamine, andpolyethylene glycol, and halogenated ethyl ethers, such as mono anddichloroethyl ether. It is to be understood that this listing of usefulhygroscopic agents is only illustrative.

Finally, since a portion of the difliculties stemming from the use ofprior art nylon fiber softeners appears to have been due to theoxidation of equipment and particularly machinery and portions thereofformed of iron and iron-base alloys, it has been found advantageous toinclude a rust inhibitor in the treating composition. When processed inequipment undergoing rusting, nylon becomes discolored from the ferrousoxide present in the system, and it has been found that the iron isexceedingly diflicult to remove from the fibers. This effect isparticularly noticeable after shut-downs normal in a Work schedule, suchas those occurring on holidays or over weekends.

Substances which have been found to prevent or minimize rust formationin equipment contacted by the composition of the present invention, whenincorporated therein, include monoethanolamine, sodium nitrite, silicateof soda, sodium chromate, and similar materials.

The following specific examples will serve to further illustrate themanner in which the invention may be applied.

A shipment of 15 denier, 6 /2 inch nylon staple, as received, wasdivided into two portions. One-half of the stock was scoured to removethe previously applied softener, Avitex R, a cationic agent applied bythe nylon supplier. The scouring bath was formulated to the followingcomposition in which the percentages are by weight:

1% tetrasodium pyrophosphate 1% sequestering agent 1% non-ionicdetergent Balance water.

The staple was scoured in the bath at 160-180 F. for 30 minutes toremove cationic agent, and then withdrawn from the bath, and rinsedwell. After rinsing, the staple was treated with a solution containing1% by weight of fatty ester of the type described above. After treatmentat 120 F. for 20 minutes, the staple was withdrawn, dried withoutrinsing and sent through the normal processing operations. The otherhalf of the stock was processed in the same manner, except that itreceived no pretreatment to remove the cationic softener applied by thesupplier, and no subsequent treatment with the formulation of thepresent invention. Both lots were processed separately into yarn byotherwise identical procedures. The carded fiber treated according tothe present invention was uniformly white and clean in appearance andwas noticeably whiter and cleaner than staple which had been cardedwithout any treatment other than that originally applied by thesupplier.

The carded fiber from each half was spun separately on the worstedsystem and the resulting yarn was conveyed to a tufting machine. Thetreated yarn was found to process with much less difliculty than thecontrol yarn, i.e., that which had not received the fatty acid estertreatment. It was noted that the untreated yarn had more fuzzy andfrayed ends and had attracted dust and loose dirt to a noticeablygreater degree than the treated yarn.

Cut pile rugs were formed of the tufted yarns by sewing onto jutebacking. The rug formed of the treated fibers was uniform in appearance'as compared with the streaky untreated fibers. The streakiness wasstill evident after dyeing in a bath of 9.0 to 9.5 pH with apremetallized color, on the untreated fibers, While the treated fibersdyed uniformly and without streakiness.

The above was repeated with diethylene glycol in the treating bath andwith both diethylene glycol and a rust inhibitor added to the treatingbath. The results were still further improved over the use of theesterified fatty acid product alone.

The procedure was repeated with the tufted pile semifinished ruglaundered in a built detergent based on tetrasodium pyrophosphate, andthereafter dyed. To retain the benefits, it was found necessary tore-treat the material with the esterified fatty acid after dyeing.

One further point should be noted; namely, that the resulting rugs, inservice, did not build up a static charge if given the treatment againafter dyeing.

The compositions of the present invention are preferably formed bydispersing the mixed esters in water, in the ratio of about 1:1:2 (fattyacid esterzdiethylene glycolzwater), together with a small amount ofrust inhibitor.

The compositions of the present invention may be applied by sprayinginstead of immersion, and may be applied to either fiber or yarn stockand/ or to finished carpeting.

A comparison of the advantages derived by the use of the treating agentsof the present invention with other presently used commercial agentsfollows:

Fifteen strips, 34 x 6" were sewed from 2.50/2 ply heat set nylon yarnon a 12 needle tufting cut pile machine. All fifteen of these sampleswere laundered with a solution containing 1% tetrasodium pyrophosphateand 1% Alkanol HCS, based on the weight of material, at the boil. Theywere rinsed, dried and each strip tested for whiteness. This testrevealed that all samples had the same whiteness reading. Two each ofthe laundered strips were treated with one of the following lubricatingand softening agents. One sample was retained as a control.

TABLE I Identification Percent Commercial Company Used Name 1 Avcospin105 Burkart-Schier. 3 Fibracon C62 Burkart-Schier. 1 M Bibb Mfg. Co. 1Nopco Chem. Co. 1 E. I. du Pont. 1 General Dyestutl. 3 Drutone BL E. F.Drew.

After application of the seven lubricating and softening agents, byimmersing the samples in a liquid bath containing such agent, thesamples were withdrawn from the bath and dried without rinsing. Thedried samples were then soiled in a soilage machine. After dischargefrom the machine they were vacuum cleaned. A whiteness reading was takenwith a Photovolt machine on which the scale readings are from 0 to 100.is the maximum whiteness recorded, smaller readings representing lesswhite material. After recording the whiteness of the samples, each ofthe samples was laundered with a built detergent and then dried in atumble type drier. The dried, laundered samples were again tested forwhiteness in the Photovolt machine. Results were as follows:

TABLE II Photovolt Reading Sample N 0.

After Soilage After Laundering 5 After treating and drying the samples,a static reading was taken on each of the treated samples with anElectro- Static Locator.

TABLE IIIELECTRO-STATIC LOCATOR (Machine legend: 1 to -10, staticgenerated; zero, n static generated; +1 to +10, static generated) Agent:Reading Xl -7 X-2 9 X-3 Zero X4 '8 X5 7 X6 X-7 8 The other seven samplestreated with the various agents were laundered; then, the jute backingwas dyed with the results shown in Table IV.

TABLE IV] UTE DYEING (Test legend: Results desired would be that thepile be uniformly stained, or, preferably, remain white) In theforegoing description, the compositions identified by trade names inTable I are identified in accordance with the definitions of theAmerican Association of Textile Chemists and Colorists as follows:

Avcospin 105Antistatic lubricant for acrylic fibers and yarns.compounded synthetic waxy sorbitol ester.

Avitex R-Cationic softener for cotton and synthetic fiber;

antistatic finish; high alkylamine.

Drutone BLFinishing cotton, nylon and other synthetics increases tearstrength. Blend of sulfated synthetic ester and coconut oil.

Fibracon C62-Fiber conditioner.

of non-staining oils and waxes.

Nopco LV-40Antistatic lubricant for synthetics. Fatty amide and ester.

Soromine CS-Cationic softener for cotton, wool and synthetic fibers.Fatty amino amide compound.

The composition identified as M-195 consisted of:

25 %A mixture of esters of stearic, oleic, and palmitic acids esterifiedwith lower glycols. Such esters are commercially available, e.g., underthe trade name Profine (Proctor and Gamble, anionic compound with afatty ester base). Other fatty esters such as Lubritone CP may be usedin place thereof provided the fatty ester product is anionic ornon-ionic.

25%Diethylene glycol 1%-S0dium nitrite, and

49%Water.

The treatment described is preferably carried out at room temperature(25 C.) or at any convenient temperature between about 10 C. and 50 C.,at which the fatty ester is in liquid form. The composition preferablyconsists of between about 25% and 30% by weight of fatty acid ester,between about and 25% by weight of diethylene glycol and between about1% and 2% by weight of a rust inhibitor, such as sodium nitrite ormonoethanolamine, and may be diluted, if desired, by the addition ofcompatible solvents, such as water.

Substantive emulsion From the foregoing detailed description it will beevident that there are a number of changes, adaptations, andmodifications of the present invention which come within the province ofthose skilled in the art; however, it is intended that all suchvariations not departing from the spirit of the invention be consideredas within the scope thereof as limited solely by the appended claims.

I claim:

1. A process for producing anti-static characteristics in nylon fiberswhich comprises: applying thereto a composition consisting essentiallyof fatty acid ester formed by the esterification of fatty acids havingat least 6 carbon atoms in the hydrocarbon chain and lower polyolsselected from the group consisting of lower glycols and lower glycerols,diethylene glycol and a rust inhibitor.

2. The process of claim 1 wherein the ester is anionic.

3. A process for producing anti-static characteristics in nylon fiberswhich comprises: applying thereto a composition consisting essentiallyof fatty acid ester formed by the esterification of fatty acids havingat least 6 carbon atoms in the hydrocarbon chain and lower polyolsselected from the group consisting of lower glycols and lower glycerols,hygroscopic agent and a rust inhibitor.

4. A process for producing anti-static characteristics in nylon fiberswhich comprises: applying thereto a composition consisting essentiallyof 25 to 30% by weight of fatty acid ester formed by the esterificationof fatty acids having at least 6 carbon atoms in the hydrocarbon chainand lower polyols selected from the group consisting of lower glycolsand lower glycerols, 5 to 30% by weight of hygroscopic agent and l to 2%by weight of rust inhibitor.

5. A process for producing anti-static characteristics in nylon fiberswhich comprises: applying thereto a composition consisting essentiallyof fatty acid ester formed by the esterification of fatty acids havingat least 6 carbon atoms in the hydrocarbon chain and lower polyolsselected from the group consisting of lower glycols and lower glycerols,hygroscopic agent selected from the group consisting of ethyleneglycols, diethanolamine and triethanolamine, glycerine and chloroethylethers, and a rust inhibitor.

6. A process for producing anti-static characteristics in nylon fiberswhich comprises: applying thereto a composition consisting essentiallyof fatty acid ester formed by the esterification of fatty acids havingat least 6 carbon atoms in the hydrocarbon chain and lower polyolsselected from the group consisting of lower glycols and lower glycerols,hygroscopic agent and a rust inhibitor selected from the groupconsisting of monoethanolamine, sodium nitrite, silicate of soda, andsodium chromate.

7. A process for producing anti-static characteristics in nylon fi herswhich comprises: applying thereto a composition consisting essentiallyof 25 to 30% by weight of fatty acid ester formed by the esterificationof fatty acids having at least 6 carbon atoms in the hydrocarbon chainand lower polyols selected from the group consisting of lower glycolsand lower glycerols, 5 to 30% by weight of hygroscopic agent selectedfrom the group consisting of ethylene glycols, ethanolamines, glycerineand chloroethyl ethers, and 1 to 2% 'by weight of rust inhibitor se-'lected from the group consisting of monoethanolamine, sodium nitrite,silicate of soda, and sodium chromate.

8. Nylon fibers having anti-static characteristics including a coatingthereon consisting essentially of a fatty acid ester formed by theesterification of fatty acids having at least 6 carbon atoms in thehydrocarbon chain and lower polyols selected from the group consistingof lower glycols and lower glycerols, hygroscopic agent and a rustinhibitor.

9. Nylon fibers having anti-static characteristics including a coatingthereon consisting essentially of 25 to 30% by weight of fatty acidester formed by the esterification of fatty acids having at least 6carbon atoms in the hydrocar- 'bon chain and lower polyols selected fromthe group consisting of lower glycols and lower glycerols, to 30% byweight of hygroscopic agent and 1 to 2% by weight of rust inhibitor.

10. Nylon fibers having anti-static characteristics including a coatingthereon consisting essentially of a fatty acid ester formed by theesterification of fatty acids having at least 6 carbon atoms in thehydrocarbon chain and lower polyols selected from the group consistingof lower glycols and lower glycerols, hygroscopic agent selected fromthe group consisting of ethylene glycols, diethanolamine andtriethanolamine, glycerine and chloroethyl ethers and a rust inhibitor.11. Nylon fibers having anti-static characteristics including a coatingthereon consisting essentially of a fatty acid ester formed by theesterification of fatty acids having at least 6 carbon atoms in thehydrocarbon chain and lower polyols selected from the group consistingof lower glycols and lower glycerols, hygroscopic agent and a rustinhibitor selected from the group consisting of monoethanolamine, sodiumnitrite, silicate of soda and sodium chromate.

12. Nylon fibers having anti-static characteristics including a coatingthereon consisting essentially of 25 to by weight of fatty acid esterformed by the esterification of fatty acids having at least 6 carbonatoms in the hydrocarbon chain and lower polyols selected from the groupconsisting of lower glycols and lower glycerols, 5 to 30% by weight ofhygroscopic agent selected from the group consisting of ethyleneglycols, diethanolamine and triethanolamine, glycerine and chloroethylethers, and 1 to 2% 'by weight of rust inhibitor selected from the groupconsisting of monoethanolamine, sodium nitrite, silicate of soda andsodium chromate.

References Cited by the Examiner UNITED STATES PATENTS 2,079,108 5/1937Dreyfus et al. 1*17l39.5 X 2,103,497 12/ 1937 Schneider.

2,436,978 3/1948 Standley et al. 117--139,5 X 2,512,949 6/1950 Lieber1064 X 2,664,409 "12/1953 Aickin et al 117--139.5 X 2,739,870 3/1956Senkus 21--2.5 2,955,960 10/1960 Batty et al. 117-139.5 X

WILLIAM D. MARTIN, Primary Examiner.

T. G. DAVIS, Assistant Examiner.

1. A PROCESS FOR PRODUCING ANTI-STATIC CHARACTERISTICS IN NYLON FIBERSWHICH COMPRISES: APPLYING THERETO A COMPOSITION CONSISTING ESSENTIALLYOF FATTY ACID ESTER FORMED BY THE ESTERIFICATION OF FATTY ACIDS HAVINGAT LEAST 6 CARBON ATOMS IN THE HYDROCARBON CHAIN AND LOWER POLYOLSSELECTED FROM THE GROUP CONSISTING OF LOWER GLYCOLS AND LOWER GLYCEROLS,DIETHYLENE GLYCOL AND A RUST INHIBITOR.